Charging and monitoring apparatus and method of charging a battery and monitoring the power level through power supply line

ABSTRACT

A battery is charged utilizing electric power provided by a power supply line included in a cable that is in accordance with IEEE 1394. A charging apparatus and a personal computer are connected together by the cable. A power source unit in the personal computer converts AC voltage to direct voltage and supplies the DC voltage to the power supply line. The voltage is applied to a charging circuit via the power supply line, thereby charging the battery. A signal line included in the cable is used when the charging apparatus and personal computer send and receive data to and from each other.

This application is a divisional of application Ser. No. 09/589,278,filed on Jun. 8, 2000 now U.S. Pat. No. 6,298,395, which is a divisionalof application Ser. No. 09/014,383, filed on Jan. 27, 1998 now U.S. Pat.No. 6,138,178, the entire contents of which are hereby incorporated byreference and for which priority is claimed under 35 U.S.C. § 120; andthis application claims priority of Application No. 9-28290 and 9-82421filed in JAPAN on Jan. 27, 1997 and Mar. 17, 1997 under 35 U.S.C. § 119.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a data communication system and method throughwhich a controller and a controlled device controlled by the controllerperform data communication via a communication channel, and to thecontroller and controlled device that construct this data communicationsystem. The invention relates further to a digital video camera andprinter. The invention relates further to a method of controlling thestorage of driver software and a method of reading out the driversoftware.

This invention relates further to a battery charging apparatus capableof being connected to a communication apparatus, which is capable ofperforming data communication via a communication channel, using thiscommunication channel to make the connection. The invention relatesfurther to a method of charging a battery.

2. Description of the Related Art

In a data communication system through which a controller (a personalcomputer) and a controlled device (a printer or digital video camera,etc.) perform data communication via a communication channel, it isnecessary to install driver software in the controller in order tocontrol the controlled device using the controller. In the prior art,the user loads a floppy disk or CD-ROM, on which driver software suitedto the controlled device has been stored, into a floppy disk drive orCD-ROM drive of the controller. The driver software is then installed inthe controller by being read out of the floppy disk or CD-ROM. However,performing installation by loading the floppy disk or CD-ROM into thefloppy disk drive or CD-ROM drive is a troublesome operation for theuser. In addition, there are occasions where the user accidentallyinstalls driver software not suited to the controlled device.

On the other hand, in order to send and receive image data, use is madeof parallel communication by relying upon a Centronics interface or SCSI(Small Computer System Interface), etc., and serial communication usingan RS232C, RS422 or USB (Universal Serial Bus). With serialcommunication, only the sending and receiving of image data is performedand consideration has never been given to charging a battery byutilizing an image-data communication channel. If a battery is to becharged, a charging device must be connected via a separate power supplycable.

SUMMARY OF THE INVENTION

Accordingly, a first object of the present invention is to so arrange itthat installation of driver software (a program for controlling aninput/output unit or for performing a data transfer with an input/outputunit) can be performed in comparatively simple fashion.

A second object of the present invention is to provide a batterycharging apparatus capable of being connected to a communicationapparatus, which is capable of performing data communication via acommunication channel, using this communication channel to make theconnection, as well as a battery charging method.

A first invention is to provide a data communication method throughwhich a controller and a controlled device controlled by the controllerperform data (inclusive of image data and audio data) communication viaa communication channel.

In accordance with this data communication method, driver software of aplurality of types is stored in a storage area of the controlled device(e.g., a digital video camera or a printer).

The controller judges whether driver software suited to the controllerhas been stored in a predetermined first storage area of the controlleddevice. In response to a judgement by the controller to the effect thatdriver software suited to the controller has been stored in thecontrolled device, the driver software suited to the controller is readout of the first storage area, data representing the driver softwareread out is transmitted from the controlled device to the controller,and the transmitted data representing the driver software is stored in asecond storage area of the controller.

A first aspect of the present invention is to provide a datacommunication system suitable for implementing the data communicationmethod described above.

The data communication system according to the present invention is forcommunication of data between a controller and a controlled device via acommunication channel.

The controlled device is provided with a first memory capable of storingdriver software of a plurality of types.

The controller comprises a second memory for storing driver software,judgement means (a judgement device) for judging whether driver softwaresuited to the controlled device has been stored in a predetermined firststorage area of the first memory, readout means (a readout device),responsive to a judgement by the controller to the effect that driversoftware suited to the controller has been stored in the controlleddevice, for reading the driver software suited to the controlled deviceout of the first storage area, transmission control means (atransmission control device) for transmitting data, which represents thedriver software read out by the readout control means, from thecontrolled device to the controller, and storage control means (astorage control device) for receiving the data representing the driversoftware transmitted by the transmission control means, and storing thisdata in a second storage area of the second memory.

The controller or controlled device constructing the data communicationsystem described above may each be constructed as a stand-alone device.

In accordance with the first aspect of present invention, driversoftware of a plurality of types is stored in the controlled devicedescribed above. It is judged whether driver software suited to thecontroller which performs data communication with the controlled devicehas been stored among the plural types of driver software. If driversoftware suited to the controller has been stored, this driver softwareis read out of the controlled device and transmitted to the controller.The transmitted driver software is stored in the controller to completeinstallation.

In accordance with the first aspect of present invention, the laborinvolved in installing driver software, which is for performing datacommunication with a controlled device, in the controller is eliminated.Installation of the driver software can be executed without atroublesome operation being required of the user. In addition, driversoftware not suited to the controlled device can be prevented from beinginstalled in the controller.

An arrangement may be adopted in which it is judged beforehand whetherdriver software suited to the controller has not been stored in thecontroller. In response to a judgement to the effect that the driversoftware has not been stored, it is judged whether driver softwaresuited to the controller has been stored in the first storage area ofthe controlled device.

If, upon judging whether installation of driver software is required ornot, it is found that installation is required, then installation iscarried out. This makes it possible to prevent the re-installation ofdriver software that has already been installed.

It is preferred that in response to a judgement to the effect thatdriver software suited to the controller has not been stored in thefirst storage area of the controlled device, information relating to theresult of the judgement is communicated to the user.

As a result, the user can be notified of the fact that driver softwarecannot be transmitted from the controlled device to the controller, as aresult of which processing for installing the driver software cannot beexecuted. In this case, the user would load a floppy disk or the like,which stores the driver software suited to the controller, into thecontroller to perform installation of the driver software.

The above-mentioned communication line may be a cable in accordance withthe IEEE (Institute for Electrical and Electronic Engineers) 1394standards, and data representing the driver software may be transmittedin accordance with IEEE 1394. As a result, the data representing driversoftware can be sent and received at a comparatively high speed.Installation of the driver software is speeded up as a result.

It is preferred that the driver software stored in the controlled devicebe rewritable. This would make it possible to update the driversoftware.

It is preferred that the address of driver software that has been storedin the first storage area and information (the operating system used bythe controller, etc.) relating to the controller capable of performingcontrol using this driver software be stored so as to be capable ofbeing read out.

By thus reading out the above-mentioned address as well as theinformation relating to the controller, the driver software can be readout again in comparatively simple fashion.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

According to a second aspect of the present invention, there is provideda charging apparatus capable of being connected to a communicationapparatus, which is capable of performing data communication via acommunication channel, using this communication channel to make theconnection, wherein the communication channel includes a communicationline for data communication and a power supply line for supplyingelectric power, the apparatus having a charging circuit for charging abattery by being supplied with electric power through the power supplyline.

According to the second aspect of the invention, there is also provideda method suited to the charging apparatus defined above.

Specifically, a method of charging a battery according to the presentinvention comprises connecting a charging apparatus, which includes acharging circuit, to a communication apparatus capable of performingdata communication via a communication channel that includes acommunication line for data communication and a power supply line forsupplying electric power, the connection being made using thecommunication channel, and charging a battery by supplying electricpower to the charging circuit through the power supply line.

In accordance with the second aspect of the invention, the chargingapparatus can be connected to a communication apparatus, which iscapable of performing data communication via a communication channel,using the communication channel. The communication channel includes acommunication line for data communication and a power supply line forsupplying electric power. Supplying the charging circuit with electricpower through the communication line makes it possible to charge abattery. A power supply cable need not be connected separately of thecommunication channel.

Preferably, it is judged, based upon the power supplying capability ofthe communication apparatus, whether charging by the charging circuit ispossible, and charging the battery by the charging circuit in responseto a judgement to the effect that charging is possible.

Preferably, it is judged, based upon the level of electric powersupplied from the power supply line, whether a decline in supplied powerwill occur in the power supply line. An adjustment is performed toreduce amount of charging by the charging circuit in response to ajudgment to the effect that a decline in the supplied power will occur.

When the power supplying capability is low, it is possible to preventdata communication from being interrupted by a decline in supplied powercaused by charging being carried out by the charging circuit.

According to a third aspect of the present invention, there is provideda charging apparatus capable of being connected to a communicationapparatus, which is capable of performing data communication via acommunication channel, using this communication channel to make theconnection, wherein the communication channel includes a communicationline for data communication and a power supply line for supplyingelectric power, the apparatus having a charging circuit for applyingelectric power, with which it is supplied through the power supply line,to a connector of a data processing unit driven by an installed battery,the data processing unit being formed to have the connector in order toinput electric power for charging the battery.

According to the third aspect of the invention, there is also provided amethod suited to the charging apparatus defined above.

Specifically, there is provided a method of charging a battery using acharging apparatus capable of being connected to a communicationapparatus, which is capable of performing data communication via acommunication channel, using this communication channel to make theconnection, wherein the communication channel includes a communicationline for data communication and a power supply line for supplyingelectric power, the method including applying electric power, which issupplied through the power supply line, to a connector of a dataprocessing unit driven by an installed battery, the data processing unitbeing formed to have the connector in order to input electric power forcharging the battery, the battery being charged by the electric powerapplied.

In accordance with the second aspect of the invention, a battery can becharged while still installed in a data processing unit driven by theinstalled battery.

Other features and advantages of the present invention will be apparentfrom the following description taken in conjunction with theaccompanying drawings, in which like reference characters designate thesame or similar parts throughout the figures thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating the electrical configuration of acommunication system according to a first embodiment of the presentinvention;

FIG. 2 illustrates the content of an EEPROM included in a device, namelythe content of a bus information block and root directory;

FIG. 3 illustrates the content of an EEPROM included in a device, namelythe content of a unit directory;

FIG. 4 illustrates the content of an EEPROM included in a device, namelythe content of a unit-specific information directory;

FIG. 5 illustrates the content of an EEPROM included in a device, namelythe content of a driver-software information directory;

FIG. 6 illustrates the content of an EEPROM included in a device, namelythe content of a driver-software archive area;

FIG. 7 is a flowchart illustrating the procedure of processing forinstalling a device driver;

FIG. 8 is a block diagram illustrating a second embodiment of thepresent invention and showing a charging apparatus, a personal computerand a communication apparatus interconnected by a cable in accordancewith IEEE 1394;

FIG. 9 illustrates the format of a self-identification packet; and

FIG. 10 is a block diagram illustrating another embodiment of thepresent invention and showing a charging apparatus, which is connectedto a digital camera, and a personal computer connected to the chargingapparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT

(1) First Embodiment

A preferred embodiment of the present invention will now be describedwith reference to the drawings.

FIG. 1 is a block diagram illustrating the electrical configuration of acommunication system according to a first embodiment of the presentinvention.

In this communication system, a device 20 (a printer or digital videocamera, etc.) and a device controller 10 for controlling the device 20are connected by a cable in accordance with IEEE 1394.

The device controller 10 has its overall operation supervised by a CPU13. The device controller 10 includes a communication control circuit 11for performing a data transfer in accordance with IEEE 1394, a displayunit 14 whose display is controlled by the CPU 13, and a memory 15 forstoring an operation program and other necessary data.

The device 20 has its overall operation supervised by a CPU 23.

The device 20 includes a communication control circuit 21 in such amanner that data transfer in accordance with IEEE 1394 is possible. Thecommunication control circuit 21 is connected to the CPU 23 via a busbridge 22. The device 20 further includes an EEPROM 24 storing driversoftware for controlling the device 20 by the device controller 10, aswell as other data (the details of which will be described later), and amain memory 25 for temporarily storing data (image data, audio data,etc.) transmitted from the device controller 10.

FIGS. 2 through 6 illustrate content stored in the EEPROM 24 of thedevice 20.

FIG. 2 illustrates the content of a bus information block and rootdirectory, FIG. 3 illustrates the content of a unit directory, FIG. 4illustrates the content of a user-specific information directory, FIG. 5illustrates the content of a driver-software information directory andFIG. 6 illustrates the content of a driver-software archive area.

As shown in FIG. 2, a bus information block stores a flag indicating thesize of the bus information block, data indicating CRC (cyclicredundancy check) data length, a CRC value of the EEPROM 24, bus name(since the device 20 and device controller 10 are connected by a cablein accordance with IEEE 1394 in this embodiment, this fact is storedhere), data representing whether communication of isochronous data isallowed or not, a reserve area, speed of the cycle clock of a cyclemaster (here the device controller 10 is the cycle master), payload sizeof isochronous data, printer maker ID and interface hardware ID.

The root directory stores a flag indicating the size of the rootdirectory, a CRC, an interface module maker ID and its data index (thedata index is an item of data which represents what the following itemof data is), a flag indicating the capability of a node (here the device20), the address of a node-unique ID (which includes the maker ID andserial number of the node) and the address of the unit directory.

As shown in FIG. 3, the unit directory stores a flag indicating the sizeof the unit directory, a CRC, a device maker ID and its index, thesoftware version of the system controller of the printer and its index,and the address of the unit-specific information directory and itsindex.

As shown in FIG. 4, the unit-specific information directory stores aflag indicating the size of the unit-specific information directory, aCRC, a command address, and its index, used when a command istransmitted from the device controller 10 to the device 20, device makername and its index, device model name and its index, and the address ofthe software information directory and its index.

As shown in FIG. 5, the driver-software information directory stores thedata length of the data that has been stored in the driver-softwareinformation directory, a CRC, the corresponding OS (operating system)name of the driver software and its major version number and minorversion number, and the storage address of the driver software. Sincedriver software of a plurality of types has been stored in thedriver-software archive area, as will be set forth below, acorresponding OS name of the driver software, major version number,minor version number and driver software storage address also are storedin dependence upon the type of driver software.

A plurality of types of driver software are stored in thedriver-software archive area illustrated in FIG. 6. Driver software oftypes “A”, “B”, “C” and “D” are stored in areas specified by addressesad1, ad2, ad3 and ad4, respectively. Thus, in the communication systemaccording to this embodiment, a plurality of types of driver softwareare stored in the driver-software archive area, and driver softwaresuited to the operating system used in the device controller 10connected to the device 20 is read out. The processing involved will bedescribed in detail later.

Installation of driver software in the device controller 10 according tothis embodiment will now be described.

FIG. 7 is a flowchart illustrating the processing procedure forinstalling driver software.

With reference to FIGS. 7 and 1, the maker name and model name of thedevice 20 connected to the device controller 10 are read (step 31). Inorder to read this information, a first reference is made to the rootdirectory shown in FIG. 2, where the address of the unit directory issensed. The unit directory is referred to based upon the address of theunit directory. The address of the unit-specific information directoryis sensed from the unit directory. The unit-specific informationdirectory is referred to based upon the address of the unit-specificinformation directory. The device maker name and device model name aresensed from the unit-specific information directory. The datarepresenting sensed device maker name and device model name is read outof the EEPROM 24 and supplied from the device 20 to the devicecontroller 10. The data representing the device maker name and devicemodel name is stored temporarily in the main memory 15 of the devicecontroller 10.

Next, it is judged whether driver software suitable for controlling thedevice 20 connected to the device controller 10 has been stored in themain memory 15 of device controller 10 (step 32). If the driver softwarehas already been stored in the main memory 15 (“YES” at step 32),processing for installing the driver software is unnecessary. Processingis terminated as a result. If the driver software has not been installedin the main memory 15 (“NO” at step 32), it is judged whether driversoftware suitable for controlling the device 20 has been stored in theEEPROM 24 of the device 20 (step 33). This judgement is made byreferring to the unit directory of FIG. 3 based upon the root directoryof FIG. 2 and to the unit-specific information directory of FIG. 4 basedupon the unit directory in a manner similar to that of the processing(step 31) for reading the device maker name and model name. The addressof the driver-software information directory is sensed from theunit-specific information directory. The driver-software informationdirectory shown in FIG. 5 is referred to based upon this address. It isjudged whether a name the same as that of the operating system runningon the device controller 10 and whether a version number the same as orlater than the version number of this operating system have been storedin the driver-software information directory. When the same name hasbeen stored as well as the same or later version number of the operatingsystem, it is judged that driver software suited to the devicecontroller 10 has been stored in the EEPROM 24 of the device 20 (“YES”at step 33).

If it is judged that driver software suited to the device controller 10has been stored in the device 20, the storage address of the suitabledriver software is sensed from the driver-software informationdirectory. Data representing the driver software suited to the devicecontroller 10 is read out of the driver-software archive area based uponthe sensed address. The data representing the driver software that hasbeen read out is transmitted from the device 20 to the device controller10 in accordance with IEEE 1394 (step 34).

The data representing the driver software is received by the devicecontroller 10 and stored in the main memory 15. This completes theinstallation of the driver software. Reading out the driver softwarethat has been stored in the main memory 15 makes it possible for theoperation (a printing operation, image data reading operation, etc.) ofthe device 20 to be controlled by the device controller 10.

If driver software suitable for control of the device 20 has not beenstored in the EEPROM 24 of the device 10 (“NO” at step 33), then amessage to this effect and a message calling for installation of thedriver software are displayed on the display unit 14 of the devicecontroller 10 (step 35). In response, the user loads a storage mediumsuch as a floppy disk storing the driver software suitable for controlof the device 20 into the floppy disk driver (not shown) of the devicecontroller 10, thereby performing installation.

In the embodiment described above, data transfer of the driver softwareis carried out based upon IEEE 1394. However, it goes without sayingthat the data transfer may be performed based upon another standard.

If the device 20 in the above-described embodiment is a digital videocamera, plural types of driver software would be stored in the digitalvideo camera and the driver software suitable for controlling the camerawould be read out of the camera and transmitted to the camera controller(device controller). If the device 20 is a printer, then plural types ofdriver software would be stored in the printer and the driver softwaresuitable for controlling the printer would be read out of the printerand transmitted to the printer controller (device controller).

Further, in the embodiment described above, driver software suited tothe device controller 10 is transmitted from the device 20 to the devicecontroller 10. However, data representing the address of the locationstoring this driver software and data representing the operating systemfor operating this driver software may be transmitted to the devicecontroller 10 in addition to the driver software. This will make itpossible to more speedily read out the driver software again merely byreferring to these items of data.

(2) Second Embodiment

FIG. 8 illustrates a second embodiment of the present invention.

As shown in FIG. 8, a charging apparatus 40, a personal computer 60 anda communication apparatus 70 are interconnected by a cable 50 inaccordance with IEEE 1394. The cable 50 includes a signal line 52 fortransmitting data and a power supply line 51 for supplying electricpower. The cable 50 includes a ground line as well, though this is notshown. Though there are four signal lines in actuality, here only one isshown in order to simplify the drawing.

The overall operation of the charging apparatus 40 is supervised by aCPU 41. A ROM 42 storing data to be sent to and received from thepersonal computer 60 is connected to the CPU 41. A communication controlcircuit 45, which is for sending and receiving data in accordance withIEEE 1394, is also connected to the CPU 41. The communication controlcircuit 45 is connected to the signal line 52.

The charging apparatus 40 includes a charging circuit 43 for charging abattery 48. The charging circuit 43 is connected to the power supplyline 51 and charges the battery 48 by electric power supplied from thepower supply line 51. The power supply line 51 is connected to amonitoring circuit 44 as well in order that the electric power suppliedfrom the power supply line 51 may be monitored. Data representing thestatus of the electric power (i.e., where it is equal to or greater thana fixed level) supplied from the power supply line 51 is applied fromthe monitoring circuit 44 to the CPU 41. It should be noted that a cablefor supplying electric power from an external power source is notconnected to the charging apparatus 40.

The overall operation of the personal computer 60 is supervised by a CPU61.

The personal computer 60 also includes a communication control circuit63 capable of sending and receiving data in accordance with IEEE 1394and connected to the cable 50. The communication control circuit 63 iscontrolled by a controller 62. The controller 62 is controlled by theCPU 61.

The personal computer 60 includes a power source unit 64. By plugging anAC plug 65 into the socket of a commercial power supply, 120-volt ACvoltage is applied to the power source unit 64. The power source unit 64converts the 120-volt AC voltage to a DC voltage of 8 to 40 volts. Thepower source unit 64 also is connected to the power supply line 51. Theconverted DC voltage of 8 to 40 volts is supplied to the power supplyline 51, whereby the DC voltage is supplied as power for driving thecharging apparatus 40 and communication apparatus 70 connected by thecable 50. It goes without saying that the DC voltage obtained by theconversion in the power source unit 64 is supplied as driving voltage toeach of the components of the personal computer 60.

The operation through which charging is carried out by the chargingapparatus 40 will now be described.

Whether the cable 50 in accordance with IEEE 1394 has been connectedbetween the charging apparatus 40 and personal computer 60 or not ismonitored by the communication control circuit 45 of the chargingapparatus 40 and the communication control circuit 63 of the personalcomputer 60. If the cable 50 has been connected between the chargingapparatus 40 and personal computer 60, a bus reset is performed andself-identification packets of the kind shown in FIG. 9 are transmittedmutually between the charging apparatus 10 and personal computer 60.(Self-identification packets naturally are transmitted between thecommunication apparatus 70 and personal computer 60 as well.)

First through fourth self-identification packets are transmitted independence upon the number of ports to which the cable 50 is connected.Here it is assumed for the sake of simplicity that oneself-identification packet is transmitted.

As shown in FIG. 9, an area 10 of the packet stores the identifier ofthe self-identification packet, an area phy ID stores an identifierspecific to the apparatus that transmits this self-identificationpacket, an area 0 stores data indicating that this is the firstself-identification packet, an area L stores data indicating whether thecommunication control circuit of the apparatus that transmits theself-identification packet is in a state in which it can receive data,an area gap cnt stores data relating to a threshold value used injudging a sub-action gap and an arbitration gap, etc., in data transferin accordance with IEEE 1394, an area sp stores data representingcapability relating to data communication speed, an area de1 stores datarelating to delay time which occurs in a case where an apparatus thathas received data transfers the data to another apparatus, an area cstores data representing whether a bus manager and isochronous resourcemanager can be implemented in data transfer in accordance with IEEE1394, an area pwr stores data indicating whether this apparatus has theability to supply electric power, as well as data indicating maximumpower consumption, areas p0 to p2 store data relating to whether anotherapparatus is connected to the port of this apparatus as a higher orderapparatus or as a lower order apparatus hierarchically speaking, an areai stores the self-identification packet of the apparatus which began busreset first, which packet includes data relating to this fact, and anarea m stores data indicating whether a self-identification packet is tofollow.

Self-identification packets of this kind are transmitted between thecharging apparatus 40 and personal computer 60 at occurrence of busreset. When the charging apparatus 40 receives the self-identificationpacket transmitted from the personal computer 60, the charging apparatus40 senses the power supplying capability of the personal computer 60stored in the area pwr of this self-identification packet. The sensedpower supplying capability and the maximum power consumption of thecharging apparatus 40 (the relevant data having been stored in the ROM42) are compared. If the power supplying capability exceeds the maximumpower consumption, the battery 48 is charged by the charging circuit 43.If the power supplying capability is less than the maximum powerconsumption, on the other hand, charging of the battery by the chargingcircuit 43 is inhibited.

In a case where the communication apparatus 70, which is a communicationapparatus other than the charging apparatus 40 and the personal computer60, are connected by the cable 50 in accordance with IEEE 1394, thereare instances where data representing the power supplying capability ofthe communication apparatus 70 will be applied to the charging apparatus40 regardless of the fact that the electric power is being supplied fromthe personal computer 60. In such case a situation may arise in whichthe electric power actually provided by the personal computer 60 fallsbelow the maximum power consumption of the charging apparatus 40. Inorder to prevent this situation, the monitoring circuit 44 in thecharging apparatus 40 shown in FIG. 8 monitors the level of the powersupplied from the power supply line 51. If the CPU 41 judges on thebasis of the signal output by the monitoring circuit 44 that a voltagedrop will be caused by charging carried out by the charging circuit 43,the charging circuit 43 is controlled by the CPU 41 so as to performcharging to such a degree that will not cause a drop in voltage.

The personal computer 60 also compares the maximum power consumption andpower supplying capability stored in the area pwr of theself-identification packet transmitted from the charging apparatus 40.If required, the personal computer 60 terminates the supply of electricpower to the charging apparatus 40.

It goes without saying that data (e.g., data relating to the state ofcharging) is sent and received by the charging apparatus 40 and personalcomputer 60 in FIG. 8 through the signal line 52 included in the cable50.

FIG. 10 is a block diagram illustrating another embodiment of thepresent invention and showing a charging apparatus 40A, which has beenconnected to a digital camera (data processing unit) 80, and thepersonal computer 60 connected to the charging apparatus 40A by thecable 50 in accordance with IEEE 1394. Components identical with thoseshown in FIG. 8 are designated by like reference characters and are notdescribed again.

The charging apparatus 40A shown in FIG. 10 is formed to have connectors46 and 47 by which the charging apparatus 40A and the digital camera 80are electrically connected to each other. Electric power supplied fromthe charging circuit 43 is applied to the connectors 46. The connector47 is connected to the CPU 41.

The digital camera 80 includes a controller 81 and sends and receivesdata to and from the charging apparatus 40A via the connector 47.(Though the digital camera 80 includes a variety of circuits, they arenot illustrated here as they have no direct bearing upon the presentinvention.) The battery 48 serving as the driving power supply isinstalled in the digital camera 80. The two ends of the battery 48 areconnected to the connectors 46.

By thus connecting the charging apparatus 40A to the digital camera 80,the battery 48 installed in the digital camera 80 can be charged usingthe charging circuit 43 included in the charging apparatus 40A.

As many apparently widely different embodiments of the present inventioncan be made without departing from the spirit and scope thereof, it isto be understood that the invention is not limited to the specificembodiments thereof except as defined in the appended claims.

1. A charging apparatus for connecting to a communication apparatus,said communication apparatus performing data communication via acommunication channel connected to a computer, said communicationchannel being used to make the connection between said chargingapparatus and said communication apparatus, said communication channelincluding a communication line for data communication and a power supplyline for supplying electric power, and said charging apparatuscomprising: a monitoring circuit for monitoring the electric power levelsupplied through said power supply line, where data representing themonitored power level is supplied to a processor in the chargingapparatus which controls the power level in the power supply line basedon the monitored power level and charging ability of said communicationapparatus; and a charging circuit for applying electric power, withwhich it is supplied through said power supply line from said computervia said communication channel, to a connector of a data processing unitdriven by a battery installed in said data processing unit, the dataprocessing unit being formed to have said connector in order to inputelectric power for charging the battery, and said data processing unitbeing freely attachable and detachable to said connector of saidcharging apparatus.
 2. A method of charging a battery using a chargingapparatus connected to a communication apparatus, which is capable ofperforming data communication via a communication channel connected to acomputer, and using said communication channel to make a connectionwherein: said communication channel includes a communication line fordata communication and a power supply line for supplying electric power,said method comprising the steps of: monitoring, by a monitoring circuitin said charging apparatus, the electric power level supplied throughsaid power supply line, where data representing the monitored powerlevel is supplied to a processor in the charging apparatus whichcontrols the power level in the power supply line based on the monitoredpower level and charging ability of said communication apparatus;applying electric power by said charging apparatus, supplied throughsaid power supply line from said computer via said communicationchannel, to a connector of a data processing unit driven by a batteryinstalled in said data processing unit, forming the data processing unitto have said connector in order to input electric power for charging thebattery, and charging said battery by the electric power applied.
 3. Themethod according to claim 2, wherein the communication channel is acable in accordance with IEEE
 1394. 4. The method according to claim 2,wherein the data processing unit is a digital camera.
 5. The methodaccording to claim 2, wherein the data processing unit is freelyattachable and detachable to said connector of the charging apparatus.6. The charging apparatus according to claim 1, wherein thecommunication channel is a cable in accordance with IEEE
 1394. 7. Thecharging apparatus according to claim 1, wherein the data processingunit is a digital camera.
 8. The charging apparatus of claim 1, whereinwithin the charging apparatus the power supply capability of saidcomputer is compared with the power consumption by said chargingapparatus, such that said battery will be charged by said chargingcircuit only if said power supply exceeds a determined maximum powerconsumption.
 9. The charging apparatus according to claim 1, wherein thecharging apparatus senses the power supplying capability of the computerand controls the charging of the battery based on the sensed power. 10.The method according to claim 2, further including sensing, by thecharging apparatus, the power supplying capability of the computer, andcontrolling the charging of the battery based on the sensed power. 11.The charging apparatus of claim 1, further including: a processor thatcontrols apparatus of the charging apparatus; a memory that stores dataassociated with the computer; and a communication controller thatcontrols communication between the processor and computer.